Electric wire connecting device

ABSTRACT

An electric wire connecting device  50  has a housing  53  as an outer body; a screw  55  that can rotate freely about a rotation axis  55   a  at a prescribed position in the housing  53  but is prevented from moving in the axial direction; a slider  57  that is threadedly engaged with the screw  55  and makes a go-movement or a return-movement in accordance with the rotation direction of the screw  55 ; a guide hole  61  through which to introduce an electric wire  59  into the housing  53 ; and a cam  63  that is in contact with a go-side surface  91  or a return-side surface  93  of the slider  57  and rotates clockwise or counterclockwise in accordance with the movement direction of the slider  57 , and presses, at a prescribed rotation position, a portion of the electric wire  59  that is located in the guide hole  61.

BACKGROUND OF THE INVENTION

The present invention relates generally to an electric wire connectingdevice and, more specifically, to a wire connecting device used forconnecting electric wires to a printed circuit board that is provided inan electronic apparatus such as a sequencer.

A technique of connecting an electric wire to a printed circuit board isknown in which the wire is wound on the shank of a screw and, the screwis then screwed into a hole in a circuit board such that the wire isheld between the bearing surface of the head of the screw and thesurface of the circuit board. In this cases there may occur a phenomenonthat during screwing, the wire is dragged as the screw is rotated. Thereis the possibility that if part of the wire being dragged is stickingout of the screw and some conductor exists in the vicinity of the screw,the wire may contact the conductor to cause short-circuiting, or themovement of the wire may damage the conductor and its connection to thecircuit board.

As a countermeasure against this problem, Japanese Patent Laid-Open No.268898/2000 discloses a technique of using a cam instead of a screw. Ascrew is used in this technique to advance the cam close to the wire andthis advancement causes the cam to press against the wire as the screwis rotated further; the screw does not serve to directly connect thewire to the circuit board. This type of cam mechanism is used in a wireconnecting device that is incorporated in an electronic apparatus aspart of it.

The wire connecting device disclosed in the above publication has ahousing as an outer body, a wire insertion hole through which tointroduce an electric wire into the housing, a cam for pressing the wirethat has been introduced while being guided by the wire insertion hole,a screw for causing the cam to function as means for pressing the wire,a manipulation hole into which a driver for rotating the screw is to beinserted, and a terminal to be joined to a circuit board of anelectronic apparatus.

If the screw is rotated by inserting a driver through the manipulationhole after the wire has been inserted into the housing through the wireinsertion hole, the screw advances or retreats in accordance with itsrotation direction.

If the screw is rotated in the advancing direction, the screw contactsthe cam in due course. If the screw is rotated further in the samedirection, the wire is pressed by the cam. The wire is pressed by thecam at a portion of the terminal to be connected to the circuit board.As a result, the wire is electrically connected to the circuit board viathe terminal.

Incidentally, in the technique described in the above publication, thecam is free to rotate when the screw is loose, that is, in the case thatthe cam is not pressed by the cam ,taking example, before the wire isconnected to the circuit board). If in this state the connecting deviceis moved, or its orientation is changed or reversed to attach it to theelectronic apparatus, the cam may rotate about a cam shaft due to itsown weight. As a result, the cam may hit the walls etc. of theconnecting device, whereby the cam or housing is damaged or sound isgenerated.

If the screw becomes loose and the cam rotates due to its own weight,the wire insertion hole may be shut by the cam, in which case theoperator may not be able to insert into the connecting device, anecessary and sufficient length of the wire.

However, it is difficult to judged, from the outside, whether the wireinsertion hole is shut by the cam. Therefore, if the operator insertsthe wire into the insertion hole without knowing that the insertion holeis shut by the cam, the advance of the wire (a stranded wire or thinwires constituting it) is obstructed, making it difficult to insert thewire further or possibly unraveling the strands at the end of the wire.

The present invention provides the following measures to solve the abovetechnical problems.

In the invention, rotation of a cam due to its own weight is prevented.To this end, the rotation of the cam is restricted by combining the camwith a slider that makes a go-movement or a return movement inaccordance with the rotation direction of a screw.

More specifically, a wire connecting device according to the inventioncomprises a housing as an outer body; a screw that can rotate clockwiseor counterclockwise about a rotation axis at a prescribed position inthe housing while is prevented from moving in an axial direction; aslider that is threadedly engaged with the screw and makes a go-movementor a return-movement in accordance with a rotation direction of thescrew; a guide hole through which to introduce an electric wire into thehousing; and a cam that is in contact with a go-side surface or areturn-side surface of the slider, rotates clockwise or counterclockwisein accordance with a movement direction of the slider, and presses theelectric wire at a prescribed rotation position.

In the wire connecting device according to the invention having theabove configuration, as the screw is rotated, the slider makes ago-movement or a return-movement in accordance with the rotationdirection of the screw while friction occurs between the threadedlyengaged portions of the screw and the slider.

The cam is in contact with the slider an rotates clockwise orcounterclockwise in accordance with the movement direction of theslider. In other words, the cam does not rotate unless the slider ismoved.

However, as described above, frictional drag occurs between thethreadedly engaged portions of the screw and the slider. Therefore, tomove the slider, external force that is stronger than the frictionaldrag should be exerted on the slider. The cam that is in contact withthe slider does not rotate unless the slider is moved. That is, the camdoes not rotate unless external force acting on the slider is strongerthan the frictional drag. It can be said that the rotation of the cam isrestricted by the slider.

Rotating the screw with a driver is not the only cause of external forcethat acts on the slider; there may occur a case that the cam exertsexternal force on the slider. For example, the weight of the cam itselfmay cause external force. In this case, the slider is moved if the forcedue to the weight of the cam itself is stronger than the frictional dragbetween the threadedly engaged portions of the screw and the slider.

There may occur a case that the guide hole through which to introducethe wire into the housing is shut by the cam. If the wire is insertedinto the guide hole in this state, the advance of the wire is obstructedas described above.

Therefore, the frictional drag between the threadedly engaged portionsof the screw and the slider should be sufficiently strong so as toprevent an event that the weight of the cam itself overcomes thefrictional drag between the threadedly engaged portions of the screw andthe slider and the cam shuts the guide hole undesirably. That is, it isdesirable that the frictional drag that occurs between the threadedlyengaged portions be set strong enough to prevent movement of the slidereven if force due to the weight of the cam itself acts on the slider.

This measure prevents the cam from moving undesirably, and hence the camcan be prevented from hitting the walls or the constituent parts of thewire connecting device. Further, there does not occur a phenomenon thatthe cam shuts the wire insertion hole. Therefore, even if the wire isinserted into the wire insertion hole without checking whether it isshut by the cam, the advance of the wire (a stranded wire or thin wiresconstituting it) is not obstructed. This effectively prevents aphenomenon that it is difficult to insert the wire into the insertionhole or a stranded wire is unraveled.

These and other objects, features and advantages of the presentinvention will be clearly understood through a consideration of thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the course of this detailed description, the reference will befrequently made to the attached drawings in which:

FIG. 1 is a side view of a wire connecting device constructed inaccordance with the principles of the present invention;

FIG. 2 is an inverted front elevational view of the wire connectingdevice of FIG. 1, taken from the direction of arrow II thereof;

FIG. 3 is a top plan view of the wire connecting device of FIG. 1 takenfrom the direction of arrow III thereof;

FIG. 4 is a cross-sectional view of the wire connecting device of FIG.3, taken along line IV—IV thereof;

FIG. 5 is the same view as FIG. 4, but the wire being inserted into awire insertion hole of the wire connecting device and prior to clampingengagement of the wire by the cam;

FIG. 6 is the same view as FIG. 5, but illustrating the structure of thewire connecting device after the wire clamping screw has been turned toadvance the cam into clamping engagement with the wire inserted in theinsertion hole; and,

FIG. 7 is a sectional view taken along line VII—VII in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An electric wire connecting device according to an embodiment of thepresent invention will be hereinafter described with reference to thedrawings.

FIG. 1 is a side view of a wire connecting device 50 that is constructedin accordance with the principles of the present invention and shownattached to a panel 64 a of an electronic apparatus 64. The connectingdevice 50 provides a connection between a plurality of electrical wires59 and circuits on a circuit board 66 that is disposed within the device64 and behind the panel 64 a thereof.

FIG. 2 is a front view of the wire connecting device 50 as viewed fromthe direction indicated by arrow II shown in FIG. 1, while FIG. 3 is aplan view of the wire connecting device 50 as viewed from the directionindicated by arrow III shown in FIG. 1. FIG. 4 is an enlarged sectionalview taken along line IV—IV in FIG. 3.

As seen from the above drawings, the wire connecting device 50 isconfigured in such a manner that various constituent members areincorporated in internal spaces 54 of a housing 53 that serves as anouter body of the wire connecting device 50.

The various constituent members of the electric wire connecting device50 include the following components. The device 50 is intended toreceive one or more electrical wires 59, and in the embodimentillustrated, the connecting device 50 may accommodate six individualwires 59. The device includes a plurality of guide holes 61, each ofwhich receives a single wire (typically a multi-strand wire). In orderto effect tightening or loosening of the wires in place within thehousing 53, screws 55 are provided that can rotate clockwise andcounterclockwise about their rotation axes 55 a in the housing 53, butwhich are prevented from moving axially. Each screw 55 has a sliders 57threadedly engaging it. The sliders 57 move forward and backward ontheir screws 55 in response to different directions of rotation of thescrew. For purposes of this disclosure, the forward movement of theslider 57 will be referred to herein as a “go” movement and is movementthat occurs from left to right in FIGS. 4–6, while the rearward movementis referred to herein as a “return” movement and is movement which ismovement from right to left in FIGS. 4–6. Rotation of the screws 55 inone direction causes a movement of the slider in either a go or returndirection, while rotation of the screws in the other direction causesthe opposite movement of the slider.

Guide holes 61 guide respective electric wires 59 into the housing 53.Cams 63 are rotatably mounted in the housing 53 and rotate in accordancewith movement directions of the sliders 57, respectively, and areprovided to press the respective wires 59 at preselected rotationpositions, respectively. Connecting-device-side terminals 70 are joinedto respective board-side terminals 68 that are provided on a circuitboard 66 shown in FIG. 4 that is provided within the electronicapparatus 64.

The housing 53 is composed of a container-shaped base 2 made of resinsuch as plastic and a cover, or cap 3, that covers the base 2. Theinternal spaces 54 of the housing 53 are defined by combining the base 2and the cover 3 together. Each internal space 54 generally consists ofthree spaces.

As shown in FIG. 4, one space is a guide hole section 54 a that isformed in the cover 3. The other two spaces are an operation section 54b which occupy most of the total internal space of the base 2 and aterminal joining section 54 c which occupy the remaining internal spaceof the base 2. The guide hole section 54 a includes both a driverinsertion hole 74 through which to insert a driver 72 to rotate thescrew 55 and the above-mentioned guide hole 61 for guiding the wires 59into the housing 53. The central axis 74 a of the hole 74 and thecentral axis 61 a of the driver insertion hole 61 are preferablyparallel with each other. The central axis 74 a of the driver insertionhole 74 is the same as the central axis 55 a of the screw 55. For thesame of convenience, these axes are shown only in FIG. 4.

The operation section 54 b is a space that accommodates the screw 55,the slider 57, the cam 63, a main portion 70 a of theconnecting-device-side terminal 70, and other related parts that areincorporated in an inner body 53 a of the housing 53.

The terminal joining section 54 c is a space (shown to the left of thepanel 64 a in FIG. 4) where a joining portion 68 a that is part of theboard-side terminal 68, and a joining portion 70 b that is part of theconnecting-device-side terminal 70 are joined to each other. A terminalinsertion cylinder that is denoted by reference numeral 69 in FIGS. 1,3, and 4 defines this space.

When the electric wire connecting device 50 is attached to theelectronic apparatus 64, the joining portions 68 a of the board-sideterminals 68 of the electronic apparatus 64 are inserted into theterminal insertion cylinders 69, respectively. As a result, the joiningportions 68 a of the board-side terminals 68 and the joining portions 70b of the connecting-device-side terminals 70 are brought into contactwith each other, respectively.

The board-side terminals 68 are supported by respective board sideterminal support cylinders 71 that are provided on the board 66 of theelectronic apparatus 64. The board side terminal support cylinders 71are fitted with the terminal insertion holes 69 of the electric wireconnecting device 50, respectively. As a result, as described above, thejoining portions 68 a of the board-side terminals 68 and the joiningportions 70 b of the connecting-device-side terminals 70 are broughtinto contact with each other, respectively.

In addition, as shown in FIG. 4, the board side terminal supportcylinders 71 have respective engagement pieces 73 to be used forattaching the electric wire connecting device 50 to the electronicapparatus 64. As shown in FIGS. 1 and 4, the electric wire connectingdevice 50 is formed with engagement arms 56 that correspond to therespective engagement pieces 73.

As seen from FIG. 3, a plurality of internal spaces 54, each of whichconsists of the three spaces 54 a, 54 b, and 54 c, are formed in thehousing 53.

As shown in FIGS. 4–6, each screw 55 is inserted in a spring washer 86and a flat washer 88 and also inserted in, in a clearance fit, in athrough-hole 84 of a support plate 82 that extends vertically from thetop wall (FIG. 4) of a wall 80 that defines the operation section 54 b.The screw 55 is somewhat longer than a half of the length dimension ofthe operation section 54 b. Before the slider 57 is threadedly engagedwith the screw 55, the screw 55 is supported by the support plate 82 ina cantilever-like manner.

The slider 57 is formed with a threaded hole 57 a at the center. Theslider 57 can slide in the axial direction of the screw 55 and is atleast partly guided in its sliding movement by a groove 58 of theinternal wall of the connecting device operation section 54 b.

A frustoconical (in a vertical cross-section) projection 87 projectsfrom a wall 57 b of the slider 57 that is located on the side closer tothe center of the operation section 54 b. The cam 63 is hooked(described later in detail) on an inclined surface 91 disposed on thefront of the slider projection 87 on the side closer to the head 89 ofthe screw 55 and its inclined surface 93 on the opposite side.

It is preferable that the strength of the frictional force actingbetween the threaded hole 57 a and the screw 55 be such as to causefrictional drag that prevents the slider 57 from moving even when forceresulting from the weight of the cam 63 itself acts on the slider 57.

The guide hole 61 is a through-hole that is formed through a portion ofthe wall 80 of the operation section 54 b that is close to the bottomwall (FIG. 4) of the wall 80. The driver insertion hole 74 is locatedabove the guide hole 61.

The cam 63 can rotate freely in the inner body 53 a of the housing 53about a rotary shaft 40 that bridges the walls of the housing 53 so asto traverse the operation sections 54 b. The cam 63 has a pressingportion 90 (FIG. 6) for pressing against the wire 59, a recess 96 thathas hooking nails, or projections 92 and 94, that engage with theopposing surfaces of the slider projection 87, and which may beconsidered to surround the top portion of the projection 87. The camalso preferably includes a stopper 98 for preventing the advance of thewires 59 once the wires 59 have been introduced into the housing 53 fora preselected length.

The slider 57 can be moved to the leftmost position in FIG. 4 byrotating the screw 55 with the driver 72. In this state, the stopper 98and its flat wire stop surface disposed thereon faces the wire guideopening 61. The stopper 98 is located behind the wire accommodatingportion 70 a 1 (i.e., on the side opposite to the guide hole 61) that ispart of the main portion 70 a of the connecting-device-side terminal 70and is provided in the operation section 54 b so as to be continuouswith the guide hole 61. The stopper 98 thus prevents further advance ofthe wire 59 in the connecting device. The wire accommodating portion 70a 1 may also be called a guide hole because it is an extension of theguide hole 61,.

As shown in FIG. 7, both side surfaces of the cam 63 is formed with aplurality of (in this embodiment, four) support projections 97 that maycontact the inner surfaces of the inner body 53 a. The supportprojections 97 are provided to secure stable rotation of the cam 63 withrespect to the inner body 53 a so that it rotates in a true fashion anddoes not wobble, or tilt, during its operation.

As shown in FIG. 4, the connecting-device-side terminal 70 is providedin the operation section 54 b on the opposite side of the cam 63 to thescrew 55 in the vertical direction.

As described above, as shown in FIG. 4, the wire accommodating portion70 a 1 for accommodating the electric wire 59 to be introduced throughthe guide hole 61 is formed as a tip portion of the main portion 70 a ofthe connecting-device-side terminal 70. The wire accommodating portion70 a 1 assumes a U-shape in a vertical cross-section and is open on thetop side. (FIG. 4.) The bottom surface of the wire accommodating portion70 a 1 is formed with wire coming-off preventive projections 100.

Next, the functions and advantages of the embodiment will be described.

To clamp a wire 59 using the connecting device 50, a screwdriver 72 isinserted into the driver insertion hole 74 and the screw 55 is rotateduntil the pressing portion 90 of the cam 63 is located above the wireaccommodating portion 70 a 1 as shown in FIGS. 4 and 5.

As a result, being guided by the groove 58, the slider 57 is retreated,that is, moved leftward. (FIG. 4.) As the slider 57 moves so, the cam 63is rotated counterclockwise about the rotation axis 40. At this time,the rear hooking piece 92 of the cam 63 is in contact with and is hookedon the surface 93 of the frustoconical projection 87 of the slider 57.The front hooking piece 94 is slightly off the surface 91. Then, thescrew 55 is rotated with the driver 72, whereby the slider 57 is movedrightward as shown in FIG. 6. As a result, the cam 63 is rotatedclockwise and the wire accommodating portion 70 a 1 of theconnecting-device-side terminal 70 is closed by the pressing portion 90.

The surface 93 of the projection 87 of the slider 57 that contacts thehooking piece 92 of the cam 63 when the wire accommodating portion 70 a1 is closed by the pressing portion 90 may be called a return-sidesurface of the slider and the surface 91 on the opposite side may becalled a go-side surface.

When the cam 63 is rotated counterclockwise by rotating the screw 55with the driver 72, the wire accommodating portion 70 a 1 that has beenclosed by the pressing portion 90 is opened, so that a wire 59 may beinserted into the guide hole 61. In this state, the stopper 98 of thecam 63 is located behind the wire accommodating portion 70 a 1 (i.e., onthe side opposite to the guide hole 61) and prevents the advance of thewire 59. The wire 59 is inserted until its end contacts the stopper 98.The length of wire insertion is set at such a length that is suitablefor the connection of the wire 59.

After the electric wire 59 has been inserted into the wire accommodatingportion 70 a 1, the screw 55 is rotated in the direction opposite to thedirection of the preceding rotation, and the cam 63 is rotatedclockwise, whereby the cam wire pressing portion 90 presses down againstthe wire 59. As a result, the wire 59 is held between the cam wirepressing portion 90 and the wire coming-off preventive projections 100,whereby the wire 59 is prevented from coming out from the wireconnecting device 50.

Conversely, to remove the wire 59 from the wire connecting device 50,the screw 55 is rotated so that the cam 63 rotate counterclockwise,whereby the pressing of the wire 59 by the pressing portion 90 iscanceled.

When the screw 55 is rotated, the slider 57 makes a go-movement or areturn-movement in the axial direction of the screw 55 in accordancewith the rotation of the screw 55 while friction is caused between thethreadedly engaged portions of the screw 55 and the slider 57. Being incontact with the slider 57, the cam 63 is rotated clockwise orcounterclockwise in accordance with the movement direction of the slider57. In other words, the cam 63 does not rotate unless the slider 57 ismoved.

However, as described above, frictional drag occurs between thethreadedly engaged portions of the screw 55 and the slider 57.Therefore, to move the slider 57, an external force that is strongerthan the frictional drag (from the screwdriver) should be exerted on theslider 57. The cam 63 that is in contact with the slider 57 does notrotate unless the slider 57 is moved. That is, the cam 63 does notrotate unless external force acting on the slider 57 is stronger thanthe frictional drag. It can be said that the rotation of the cam 63 isrestricted by the slider 57.

Rotating the screw 55 with the driver 72 is not the only cause ofexternal force that acts on the slider 57; there may occur a case thatthe cam 63 exerts external force on the slider 57. For example, theweight of the cam 63 itself may cause external force. In this case, theslider 57 is moved if the force exerted on the slider 57 by the cam 63is stronger than the frictional drag between the threadedly engagedportions of the screw 55 and the slider 57.

There may occur a case that the wire accommodating portion 70 a 1 isshut by the cam 63. If a wire 59 is inserted into the wire accommodatingportion 70 a 1 in this state, the advance of the wire 59 is obstructed.

Therefore, the frictional drag between the threadedly engaged portionsof the screw 55 and the slider 57 should be sufficiently strong so as toprevent an event that the weight of the cam 63 itself overcomes thefrictional drag between the threadedly engaged portions of the screw 55and the slider 57 and the cam 63 shuts the wire accommodating portion 70a 1 undesirably. This measure prevents the cam 63 from movingundesirably, and hence the cam 63 can be prevented from hitting thewalls or the constituent parts of the electric wire connecting device50. Further, there does not occur a phenomenon that the cam 63 shuts thewire accommodating portion 70 a 1 before a wire 59 is inserted into it.Therefore, even if the wire 59 is inserted into the guide hole 61without checking whether the wire accommodating portion 70 a 1 is shutby the cam 63, the advance of the wire 59 (a stranded wire or thin wiresconstituting it) is not obstructed. This effectively prevents aphenomenon that it is difficult to insert the wire 59 into the wireaccommodating portion 70 a 1 or a stranded wire is unraveled.

As described above, according to the invention, the cam does not rotateundesirably and hence a phenomenon that the wire insertion hole of theelectric wire connecting device is shut by the cam can be prevented.Therefore, when an electric wire is inserted into the wire insertionhole, the advance of the electric wire (a stranded wire or thin wiresconstituting it) is not obstructed. This prevents a phenomenon that itis difficult to insert an electric wire into the wire accommodating holeor a stranded wire is unraveled.

While the preferred embodiment of the invention have been shown anddescribed, it will be apparent to those skilled in the art that changesand modifications may be made therein without departing from the spiritof the invention, the scope of which is defined by the appended claims.

1. An electrical wire connecting device, comprising: an insulativehousing; a screw mounted for rotation in the housing, the screw beingcapable of selective rotation in a first or second direction about arotational axis at a preselected level with said housing, said screwbeing restrained from axial movement within said housing; a slidersupported within said housing and engaged with said screw and capable offorward or rearward axial movement within said housing in accordancewith the screw rotation direction; a guide hole disposed in said housingspaced apart from said screw, the guide hole providing a passage intosaid housing which receives an electrical wire inserted into saidhousing, said housing further including a conductive contact proximateto said guide hole for contact the wire inserted into said guide hole,said conductive contact being electrically coupled to terminals thatextend from said electrical wire connecting device and that are capableof being coupled to a circuit board; and, a cam for selectively pressingsaid wire inserted into said guide hole into electrical contact withsaid contact, the cam including a body portion rotatably mounted withinsaid housing, the cam including a wire-contacting portion for pressingsaid wire inserted into said guide hole against said contact, said camwire-contacting portion rotating into pressing engagement with said wirewhen said screw is turned in said first direction and said slider movesin a forward direction and said cam wire-contacting portion rotating outof pressing engagement with said wire to permit said wire to be removedfrom said guide hole when said screw is turned in said second directionand said slider moves in a rearward direction, whereby frictional dragbetween said screw and slide, prevents the cam weight from rotating thecam to obstruct insertion of a wire into the guide hole, said sliderincluding a threaded hole that threadedly engages said screw, andwherein said frictional drag acting between said screw and the threadedhole opf said slider prevents said slider from moving without rotatingsaid screw.
 2. The wire connecting device according to claim 1, whereinsaid guide hole and said screw are parallel to each other within saidhousing.
 3. The wire connecting device according to claim 1, whereinsaid cam includes at least two projections extending transversely fromsaid cam body toward opposing walls of said housing, the projectionsmaintaining substantially true rotation of said cam within said housing.4. The wire connecting device according to claim 1, wherein said guidehole includes a lead in surface.
 5. The wire connecting device accordingto claim 1, wherein said slider includes a projection disposed thereon,and wherein said cam includes a recess disposed on the cam body, the camrecess receiving the slider projection therein.
 6. The wire connectingdevice according to claim 5, wherein said slider projection isfrustoconical.
 7. The wire connecting device according to claim 5,wherein said cam recess includes a pair of opposing hook surfaces thatproject partially into said cam recess, the cam cavity hook surfacesengaging said slider projection from opposite directions.
 8. The wireconnecting device according to claim 1, wherein said contact defines asurface of said guide hole.
 9. The wire connecting device according toclaim 8, wherein said contact projects rearwardly of said housing. 10.The wire connecting device according to claim 1, wherein said camincludes a stopper that is moved into said guide hole by rotation ofsaid screw in said second direction, the stopper preventing insertion ofsaid wire into said guide hole a distance more than a preselectedlength.
 11. The wire connecting device according to claim 10, whereinsaid cam wire-contacting portion and said cam stopper are spacedcircumferentially apart from each other on said cam body.
 12. Anelectrical wire connecting device, comprising: an insulative housing; ascrew mounted for rotation in the housing, the screw being capable ofselective rotation in a first or second direction about a rotationalaxis at a preselected level with said housing, said screw beingrestrained from axial movement within said housing; a slider supportedwithin said housing and engaged with said screw and capable of forwardor rearward axial movement within said housing in accordance with thescrew rotation direction; a guide hole disposed in said housing spacedapart from said screw, the guide hole providing a passage into saidhousing which receives an electrical wire inserted into said housing,said housing further including a conductive contact proximate to saidguide hole for contact the wire inserted into said guide hole, saidconductive contact being electrically coupled to terminals that extendfrom said electrical wire connecting device and that are capable ofbeing coupled to a circuit board; and, a cam for selectively pressingsaid wire inserted into said guide hole into electrical contact withsaid contact, the cam including a body portion rotatably mounted withinsaid housing, the cam including a wire-contacting portion for pressingsaid wire inserted into said guide hole against said contact, said camwire-contacting portion rotating into pressing engagement with said wirewhen said screw is turned in said first direction and said slider movesin a forward direction and said cam wire-contacting portion rotating outof pressing engagement with said wire to permit said wire to be removedfrom said guide hole when said screw is turned in said second directionand said slider moves in a rearward direction, said cam includes astopper that is moved into said guide hole by rotation of said screw insaid second direction, the stopper preventing insertion of said wireinto said guide hole a distance more than a preselected length.
 13. Anelectrical wire connecting device, comprising: an insulative housing; ascrew mounted for rotation in the housing, the screw being capable ofselective rotation in a first or second direction about a rotationalaxis at a preselected level with said housing, said screw beingrestrained from axial movement within said housing; a slider supportedwithin said housing and engaged with said screw and capable of forwardor rearward axial movement within said housing in accordance with thescrew rotation direction; a guide hole disposed in said housing spacedapart from said screw, the guide hole providing a passage into saidhousing which receives an electrical wire inserted into said housing,said housing further including a conductive contact proximate to saidguide hole for contact the wire inserted into said guide hole, saidconductive contact being electrically coupled to terminals that extendfrom said electrical wire connecting device and that are capable ofbeing coupled to a circuit board; and, a cam for selectively pressingsaid wire inserted into said guide hole into electrical contact withsaid contact, the cam including a body portion rotatably mounted withinsaid housing, the cam including a wire-contacting portion for pressingsaid wire inserted into said guide hole against said contact, said camwire-contacting portion rotating into pressing engagement with said wirewhen said screw is turned in said first direction and said slider movesin a forward direction and said cam wire-contacting portion rotating outof pressing engagement with said wire to permit said wire to be removedfrom said guide hole when said screw is turned in said second directionand said slider moves in a rearward direction, said slider including aprojection disposed thereon, and wherein said cam includes a recessdisposed on the cam body portion, the cam recess receiving the sliderprojection therein.